Method of forming an opening device comprising a slot and a strip passing through it



Aug. 19, 1969 s. o. s. STARK ETAL 3,452,334

METHOD OF FORMING AN OPENING DEVICE COMPRISING A sum? AND A STRIP PASSING THROUGH IT Original Filed July 1, 1966 2 Sheets-Sheet 1 BYM n.

ATTORNEY Aug. 19, 1969 S. O. S. STARK ETAL METHOD OF FORMING AN OPENING DEVICE COMPRISING A SLOT AND A STRIP PASSING THROUGH IT Original Filed July 1, 1966 2 Sheets-Sheet 2 INVENTOR S v SVEN 0. s. STAR K HANS G. W. MELLE THORSTEN L. LINDH BY ATTORNEY United States Patent METHOD OF FORMING AN OPENING DEVICE COMPRISING A SLOT AND A STRIP PASSING THROUGH IT Sven Olof Soren Stark, Hans-Georg Wilhelm Melle, and Thorsten Lennartson Lindh, Lund, Sweden, assignors to AB Tetra Pak, Lund, Sweden, a Swedish company Original application July 1, 1966, Ser. No. 562,300, now Patent No. 3,416,716, dated Dec. 17, 1968. Divided and this application Jan. 8., 1968, Ser. No. 713,554

Int. Cl. 1332b 31/18 US. Cl. 156-256 1 Claim ABSTRACT OF THE DISCLOSURE Method to provide sheet material with an opening device therein by punching a substantailly U-shaped opening therein and lifting the tongue formed and heating an additional strip of material to both the tongue and the sheet material.

This is a division of application Ser. No. 562,300, filed July 1, 1966, now U.S. Patent No. 3,416,716, issued Dec. 17, 1968.

The present invention relates to an opening device for packages or the like and comprising a slot passing through the packaging material, the characteristic feature of the invention being a strip passing through the slot and being attached to either side of the packaging material.

This strip is in the first place meant to have two functions, vis. to seal the said slot and in particular its cut surfaces, and to facilitate the opening of the package by acting as a pulling flap.

Preferably, the opening device according to the invention is meant to be used in connection with packages of the kind manufactured by pressing a tube fiat and sealing it transversely and possibly by shaping it thereafter to for instance parallelepipedic form. This is achieved by giving a U-shape to the slot, whereby there is formed a tongue beneath which the strip is inserted in such a way that its ends will project through the respective legs of the U. The U-shaped slot is placed in such a relation to the lines along which the transverse sealing and the separation of the packages take place that the bottom of the slot will lie parallel to the said lines, which are preferably caused to extend across or adjacent the free ends of the legs of the U.

Preferably, both the packaging material and the strip have heat-scalable plastic on both sides, whereby the strip can be attached to either side of the slot by heat-sealing between two heating jaws, which may e.g. be covered with Teflon. The result is that the strip will seal the cut surfaces of the packaging material, whose carrying interior intermediate layer normally consists of a fibrous material which will easily absorb liquid. However, the carrying material of the strip is a material which does not absorb liquid, e.g. regenerated cellulose or the like. Alternatively, on that portion which is located inside the package the strip may be covered with a plastic layer or the like, which together with a corresponding interior layer of the package is allowed to form an inner lining which is completely impervious to liquids. In the latter case, the material for the strip may be selected irrespectively of the sealing function.

When the slot is U-shaped the insertion of the strip may be facilitated if the packaging material while still in the nature of a web, i.e. prior to the tube forming operation proper, is laid in such a Way over a roller that the tongue formed by the slot will project tangentially from the roller, at the same time as the legs of the U coincide with the periphery of the roller.

3,462,334 Patented Aug. 19, 1969 Further objects and advantages of the invention will be apparent from the accompanying drawings, which show a couple of embodiments of the invention, chosen by way of example, and where FIGURE 1 shows part of a web of a packaging material prepared for the manufacturing of package according to the invention;

FIGURE 2 shows, on a larger scale, a package made from the web shown in FIGURE 1;

FIGURE 3 shows, on a still larger scale, how the web according to FIGURE 1 can be laid over a roller for facilitating the insertion of a strip into the U-shaped slots;

FIGURE 4 shows a section through the web where the said strip has been attached to both sides of the slot by heat-sealing;

FIGURE 5 shows a section corresponding to that shown in FIGURE 4 in an alternative embodiment;

FIGURE 6, finally, shows an opened package differing somewhat from the closed package shown in FIGURE 2.

The web 1 shown in FIGURE 1 and consisting of a packaging material, consists, as is shown in greater detail in FIGURE 3, of a carrying material 2 of e.g. paper, which is coated on both sides with plastic layers 3 and 4. In the web 1 there are punched U-shaped slots 5 whose bottoms are designated 6 and whose legs are designated 7. Through these U-shaped slots 5 there are formed tongues 8 beneath which strips 9 are inserted, as shown at the top in FIGURE 1. The insertion of the strips 9 beneath the tongues 8 is preferably facilitated, as shown in FIG- URE 3, by placing the web 1 around a roller 10', whereby the strips '8 will project tangentially from the roller. The strips 9 preferably consists of a non-fibrous carrying layer 11, e.g. regenerated cellulose, which is coated on both sides with layers 12 and 13 of heat-scalable plastic. Thereby the strip 9 can be attached to the web 1 on both sides of the slot by heat sealing between e.g. Teflon covered heating jaws, whereby the opening device will obtain the appearance shown in FIGURE 4. It should be observed, however, that the thickness of the strip 9 has been considerably enlarged in FIGURES 3 and 4 for the sake of better clarity. The same applies to the size of the slot 5 and the strip 9 in FIGURE 1.

From the web-shaped packaging material 1 shown in FIGURE 1 there are produced packages of the kind shown in FIGURE 2 by tube-shaping, transverse sealing and suitable after-shaping operations. The package shown in FIGURE 2 consists of a parallelepipedic body which is delimited by later surfaces 14 and end surfaces 15, there being shaped, at the forming of the package, double-walled triangular flaps 16 projecting from the end surfaces 15 of the package. The said flaps are normally folded inward toward the lateral walls or the end walls. As. will appear from FIGURE 2, there is formed at the transverse sealing operation a sealing fin 17 extending across the end surfaces 15 and beyond the flaps 16. The U-shaped slot 5 and the tongue 8 formed thereby are disposed, in the embodiment shown in FIGURE 2, in such a way that the bottom line 6 of the U is located parallel to the base line 18 of the fin between the said line and the upper border line 19 of the fin. The latter line, which is designated in FIGURE 1 by means of dash and dot lines, extends in the shown embodiment a cross the free ends of the U legs 7. If the transverse sealing is carried out along the line marked with the arrows A-A in FIGURE 1, there will be no sealing problems. Otherwise, such problems may arise precisely with regard to the free ends of the U-shape slot 5.

FIGURE 5 shows how a strip 9a passing through a packaging material 1a can be sealed on the inside of the package by means of a coated layer 20a. This may be advisable where the strip 9a does not consist of a completely liquid-repelling material or where it is desirable to achieve additional security against leakage, e.g. when the opening device is unsuitably located on the package.

Finally, FIGURE 6 shOWs a package which essentially agrees with the package shown in FIGURE 2. However, it differs from the said package as a result of the bottom line 6b of the U-shaped slot having been placed on the end surface 15b proper, i.e. outside the base line 18b of the fin 1%. Furthermore, the legs 7b and 7c of the U-shaped slot have been displaced laterally in relation to each other, whereby the package has obtained an opening which can be said to be divided into two parts, viz. the emptying opening 21b proper and a venting slot 22b departing therefrom and facilitating the emptying operation.

Of course, the invention is not restricted to the embodirnent discussed above but may be varied within the scope of the claims. Thus, FIGURE 4 is meant to show a transverse section through the strip 9 but may instead be considered to show a longitudinal section through it. In that case. FIGURE 4 shows how a strip can be displaced with its free ends first through the slot. It has furthermore been assumed that the material used above is laminated with heat-scalable plastic. Alternatively, however, it is possible to apply the invention to uncoated materials, in which case the sealing can be achieved by means of adhesive or the like. In addition, the shape and position of the slot may, of course, be varied in dependance on the package to which the invention is to be applied. Finally, it has turned out to be advisable in certain cases with regard to the embodiment shown in FIGURE 6 to let the opening 215 and 22b occupy the opposite position on account of tensions in the fin 19b.

That which is claimed is:

1. The method of forming an opening device in a sheet of material comprising the steps of providing a supply of sheet material, forming a tongue in said sheet material by cutting a U-shaped slot therein, laying said sheet material around a roller to cause said tongue to project tangentially from the roller, inserting a strip of heat sealable material under said tongue as it projects tangential from said roller and heat sealing said strip of material to said sheet material.

References Cited UNITED STATES PATENTS 2,123,262 7/1938 Townsend 229-51 2,684,807 7/ 1954 Gerrish 229-66 2,789,640 4/1957 Beldcn. 3,066,063 11/1962 Ecklund et a1. 156218 XR FOREIGN PATENTS 602,506 5/1948 Great Britain. 679,780 2/1964 Canada.

EARL M. BERGERT, Primary Examiner G. W. MOXON II, Assistant Examiner 

